Busway plug clamp



Feb. 25, 1964 c. J. ATKlNsoN 3,122,603

BuswAY PLUG CLAMP Filed NOV. 2l, 1962 2 Sheets-Sheet 1 ATTORNEY.

c. J. ATKINSON BUSWAY PLUG CLAMP Feb. 25, 1964 2 Sheets-Sheet 2 Filed NOV. 21, 1962 United States Patent O arrastra EUSWAY PLUG CLAMP V Christopher lll. Atkinson, Canoga Fark, Calif., assigner to General Electric Company, a corporation of New York Filed Nov. 21, 1962, Ser. No. 239,261 4 erstma. tot. 17a-so) This invention relates to power takeoff devices of the plug-in type which are removably mounted on the housings of busways of an electrical distribution system and it has for an object the provision of means for facihtatmg the attachment of the plug-in device to the housing and removal therefrom.

Conventional plug-in devices are provided with stab type contact members which engage the electrical bus bars inside the housing when the plug-in device is mounted on the busway in correct power take-oil position. Usually the busway is suspended from an overhead support in an elevated position which is above the heads of workmen who mount the plug-in devices on the busway.

ln the conventional practice of mounting plug-in devices on busways, the plug-in device is provided with four loating clamps commonly known as hanger hooks. These hooks are set in position manually. The plug-in device is then lifted to busway height, accurately positioned with respect to the stab openings in the housing and nally plugged into its operating position. After plugging in, the device must be held accurately in position at both ends while the hanger hooks are individually tightened by means of a screw driver. Owing to such factors as the height ot the busway above the floor, the size and weight oi the plug-in device, the necessity for accurate individual positioning and individual tightening of four separate hanger hooks, mounting a plug-in device by the conventional method is a very slow and diicult operation. Accordingly, a further object of this invention is the provision on the plug-in device of a simple clamping means that will enable installers to mount the plug-in device in a selected operating position on the busway without having to set the positions of and to tighten hanger hooks individually and to remove the plug-in device with out having to loosen them individually.

ln certain industries, such, for example, as the motion picture industry and the television industry, frequent changes in location of the plug-in device on a distribution busway is required. Accordingly, another object of the invention Lis the provision on a plug-in device of simple clamping means that enables the plug-in device to be clamped to the busway or removed therefrom in a minimum time.

A still more speciiic object of the invention is the provision on a plug-in device of a clamping device by means of which the plug-in device may be quickly clamped into operating position on the busway and equally quickly unclamped therefrom without the use of any tools.

Still another object of the invention is the provision on a plug-in device of a clamping means that enables a plugin device to be clamped to a busway or unclamped therefrom by the simple operation of moving an operating handle through a predetermined angle from one operating position to another.

ln carrying the invention into etlect in one form thereof, a pair of clamping assemblies are provided for each busway plug-in unit. On each of the end walls of the enclosure of the plug-,in device is mounted one of these clamping assemblies. Each of these assemblies comprises an operating handle pivotally mounted on the end wall for pivotal movement between two limiting operating positions together with two clamping members each provided with a hook for engaging the housing of a busway. Means are provided on the enclosure of the plug-in device for slidably mounting the clamping members in spaced apart relationship to straddle the busway housing on which the plug-in device is to be mounted and to guide the movement of the clamping members in a direction generally perpendicular to the base plate of the enclosure of the plug-in device and inwardly toward each other. A linkage interconnects the operating handie and the clamping members to effect clamping engagement of the clamping hooks with the busway housing in response to movement of the operating handle to one of its operating positions.

For a better and more complete-understanding of the invention, reference should now be had to the tollowing speciiication and to the accompanying drawings ot which:

FIG. l is a view in front elevation of a plug-in unit provided with clamping means embodying the invention.

FIG. 2 is a view in end elevation of the plug-in device and clamping means of FlG. l showing the clamping means in the fully clamped position.

FIG. 3 is a View in perspective of the plug-in device and clamping means of FEGS. l, 2 and 4 illustrating the clamping means in the fully clamped or closed position and FlG. 4 is a partial end view illustrating the clamping means in the fully unclamped or open position.

Referring now to the drawing, a plug-in device l is illustrated as mounted on an electrical distribution busway 2. The busway is of the plug-in type and is provided with a plurality ot' bus bars 3. These are so mounted and arranged within the metal housing ftof the busway that they are engaged by stab contacts 5 and with which the power take-ntl devices within the enclosure of the plug-in device are provided. Although only one stab contact 5 is iilustrated in FIG., l, it will he understood that another similar stab contact is directly behind the illustrated contact 5 and hence is not visible in FIG. l. The bus bars 3 are supported by insulation 7 and are lirmly and snugly held between the top and bottom halves of the busway housing d. These upper and lower halves are provided with longitudinal extending lateral langes which are securely held together by suitable fastening means (not shown). Usually the busway is mounted with the long dimension of the cross section disposed vertically so that the plug-in movement of the plug-in device is horizontal. The busway may be suspended from a ceiling or overhead support by means of hangers (not shown).

The plug-in unit comprises a metal enclosure having a base plate la, side walls lb and le, end =walls ld and le and a cover plate divided into two sections 1f and Iig. A power take-oil device such as a switching device is mounted within the enclosure of the plug-in device. This switching device may be of any suitable type, eg., it may be a molded case circuit breaker. Such a circuit breaker is connected to the stab contacts 5; thus it is connected to the bus bars 3 when the plug-in device is plugged into its operating position on the busway.

For the purpose of preventing damage to the stab contacts and to other externally mounted parts, the plug-in device is provided with protective frame work assemblies `S, 9 and 1G and a yfourth assembly not illustrative in the drawing. These are individually located at either end and on either side of the longitudinal center line of the plug-in device enclosure. The frame work assembly S is illustrated as comprising two U-shaped brackets `Sa and Sb made of steel strap or bar or other suitable material. These are secured to the base plate of the enclosure by any suitable fastening means, eg., they may he bolted or welded thereto. Secured to the lower legs of the U- shaped members 8a and Sb and to the base plate of the enclosure is a third member 3c having an upright leg and a horizontal leg curved upwardly at one end so that it has a sled runner configuration. Preferably the frame 35 works 8, 9, itl and the nniliustrated fourth 4frame work are identical; consequently the preceding description of the :framework assembly 8 applies to the others.

For the purpose of clamping the plugin device to the busway d, clamping assemblies l2 and 3 3 are mounted on the end panels la' and le respectively oi the plug-in device enclosure. The clamping assembly l2 comprises a bell crank ld pivotally mounted on end panel ld and is provided with an operating handle ida together with a pair of clamp members il' and le disposed to straddle a busway such as the busway 2 on which the plug-in device is to be mounted. As shown, the clamp member i7 comprises an elongated bar portion together with an integral hook portion l'a extending therefrom yat a suitable angle that may be approximately 45 degrees. This angularly disposed hook portion is provided with a cam slot 17!) and the clamping member i7 is movably mounted on the leg b of the protective frame work by means of a cam guide member I9. The clamping member lli is identical with clamping member li and is similarly mounted on a leg of the protective frame work assembly 9 by means of a Cam guide member Ztl. Both clamping hook members i7 and il@ are mounted so that the angularly disposed hook portions 17a `and extend inwardly toward each other.

Interconnecting the clamping members i7 and 18 and the handle operated bell crank lil is a linkage system that comprises end overlapping levers 2i and 22 pivotally mounted on end panel la and `a link member 23. One end of this link is pivotally connected by pin and slot connections to the overlapping levers 21 and 22 and its other end is pivotally connected to the end of the bell crank ld opposite from the handle end. As seen most clearly in FIGS. 2, 3 and 4 each ot the overlapping ends of levers 2i and 22 is provided with a slot and the adjacent end of link 23 is provided with a pin 2d that passes through and cooperates with both slots to provide a loose connection to permit rotation of levers 2l and Z2. in response to rectilinear motion of link 23. In the fully clamped position of the clamping assembly the handle arm of bell crank id rests against a stop member 25. The clamping assembly 13 mounted on the opposite end panel ie is identical with clamping assembly i4; accordingly, in order to avoid repetition a description thereof is omitted.

For the purpose of compensating `for variations in manufacture and normal wear of the parts, adjustability is imparted to the clamping assembly by making the link 23 of two overlapping pieces secured together by bolts. The bolt holes in one of the pieces are enlarged to provide for sliding the pieces with respect to each other to obtain the desired effective length and then tightening the bolts.

Handles 2e and 27 are provided on the end panels vfor the purpoes of facilitating the eiforts of the installers in lifting the plug-in device to the proper height and pushing it into its plugged in position.

With the foregoing understanding of the elements and their organization, the manner in which the plug-in device is clamped to a busway and unclamped therefrom will readily be understood from the following description.

Assuming that the plug-in device .1 is to be plugged into a plug-in type busway such as busway 2, the operating handle Ist-a on end panel la. of the enclosure and its counterpart on the opposite end panel le are rotated to the unclamped or fully open position that is illustrated in FIG. 4. In this position the link 23 is in its maximum upward limiting position and the levers 21 `and 22 are rotated about their pivots in counterclockwise and clockwise directions respectively so that both are in substantial alignment as illustrated in FiG. 4. As a result the clamping hook members i7 and IS are in their maximum downward and outward retracted positions.

The plugging in operation is quickly accomplished and in a very simple manner by raising the plug-in device to the height of the buswa plugging its stab contacts into the stab openings in the busway and rotating the handle ida and bell crank 14 in a clockwise direction toward the stop pin 25. T his rotation of the bell crank depresscs the link 23 which in turn effects clockwise rotation of lever 2l and counter clockwise rotation of lever 22. As a result, the clamping members 17 and itl are moved upwardly, i.e., toward the cover plate and are simultaneously moved inwardly toward each other. As point a on the hell crank approaches dead center, the cam hooks "17a and i351 are brought securely against the underside of busway housing flanges 4a and 4b. After point a passes dead center, the bell crank snaps against the stop pin 25 and the cam hooks are locked in the fully clamped position. A similar operation of the clamping `assembly I3 on end panel le moves and clamps the cam hooks of that assembly against the underside of the busway ange To move the plug-in device to a new location it is necessary only to rotate the operating handles in the reverse direction, i.e., away from the stop pins and withdraw the stab contacts from engagement with the bus bars. The plug-in device is then moved to the new location and the procedure described above is repeated.

rThus the plug-in device may be quickly clamped into plugged in position on a busway or quickly unclamped therefrom with a minimum of time and effort and without the use of any tools.

Alterations and modifications may be made in the above described construction without departing from the true spirit of the invention or from the scope of the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination,

(l) an enclosure for a busway plug-in device having a base plate and end walls,

(2) a pair of clamping assemblies for clamping said enclosure to a busway housing wit s id base plate against a wall of said housing,

(3) each of said clamping assemblies being mounted on a different one of said end walls and comprising (a) an operating handle pivotally mounted on the associated end wall for movement between two limiting positions,

(b) a pair of clamping members provided with hooks for engaging said housing,

(c) means on said enclosure slidably mounting said clamping members in spaced apart relationship to straddle said busway housing and to provide for movement of said members having a component generally perpendicular to said base plate, and

(d) a linkage mounted on said end wall interconnecting said clamping members and said operating handle to effect clamping engagement of said clamping members with said busway housing in response to movement of said operating handle to one of said limiting positions.

2, In combination (l) an enclosure for a busway plug-in device having a base plate and end walls,

(2) a pair of clamping assemblies for clamping said enclosure to a busway housing with said base plate against a wall of said housing,

(3) each of said clamping assemblies being mounted on a diiferent one of said end Walls and each comprising (a) an operating handle pivotally mounted on the associated end wall for movement between twO limiting operating positions,

(b) a pair of clamping members each provided with a hook for engaging said busway housing,

(c) means on said enclosure slidably mounting said clamping members in spaced apart relationship to straddle said busway housing and to provide for movement of said members having a component generally perpendicular to said base plate and a second component generally parallel thereto and (d) a linkage mounted on said end Wall interconnecting said clamping members and said operating handle to effect movement of said hook members toward each other and toward said n housing thereby to eect clamping engagement of said hooks with said busway housing in response to movement of said operating handle to one of said limiting positions.

i 3. In combination,

(1) an enclosure for a busway plug-in device having a base plate and end Walls, y

(2) a pair of clamping assemblies for clamping said enclosure to a busway housing with said base plate against a Wall of said housing,

(3) each of said clamping assemblies being mounted on a diierent one of Said end walls and comprising (a) an operating handle pivotally mounted on the associated end Wall for movement between tWO limiting positions,

(b) a pair of clamping members each comprising a ybar member having a hook extension 'for engaging said housing, said extension being provided with a cam slot,

(c) means for slidably mounting said clamping members in spaced apart relationship to straddle said busway housing and to provide for movemerit of said members having a component generally perpendicular to said base plate andy a second component generally parallel thereto comprising a pair of cam guides, one for each of said slots, and means on said enclosure mount* ing said cam guides in cooperative relationship with said cam slots and s in response to movement of said operating handle to one of said limiting positions. 4. ln combination with a busway plug-in device hawing side Walls and end walls, a pair of assemblies for clampinor said plug-in device to a busvvay housing provided with longitudinally extending lateral anges, eachy of said assemblies being mounted on a diierent one of said end walls and each comprising (l) `a pair of operating levers pivotally mounted on the associated end Wall with an end portion of one of said levers overlapping an end portion of the other; (2) elongated slots in said overlapping end portions, (3) a bell crank pivotally mounted'on said end Wall for rotation through a limited range,

(4) a connecting link provided at one end with' a pin engaging said slots and having `its other end pivotally connected to one arm of said bell crank, (5) a pair of clamping members each having an end pivotally connected to a difieren-t one of the non overlapping ends of said operating levers yand each of said clamp members having a hook extension at its opposite endtfor engaging said anges and (6) means on said plug-in device for slidably mounting smid clamping ymembers in spaced apart relationship for stralddling said busway housing to provide for engagement of said 'hook extensions in clamping relationship with said housing l:flanges in response to rotation of said bell crank to one of its limiting positions.

No references cited. 

1. IN COMBINATION, (1) AN ENCLOSURE FOR A BUSWAY PLUG-IN DEVICE HAVING A BASE PLATE AND END WALLS, (2) A PAIR OF CLAMPING ASSEMBLIES FOR CLAMPING SAID ENCLOSURE TO A BUSWAY HOUSING WITH SAID BASE PLATE AGAINST A WALL OF SAID HOUSING, (3) EACH OF SAID CLAMPING ASSEMBLIES BEING MOUNTED ON A DIFFERENT ONE OF SAID END WALLS AND COMPRISING (A) AN OPERATING HANDLE PIVOTALLY MOUNTED ON THE ASSOCIATED END WALL FOR MOVEMENT BETWEEN TWO LIMITING POSITIONS, (B) A PAIR OF CLAMPING MEMBERS PROVIDED WITH HOOKS FOR ENGAGING SAID HOUSING, 